Electrical reduction-furnace.



R. E. PRIOKEY. ELECTRICAL REDUCTION FURNACE.

APPLICATION FILED APR.29,'1L12.

Patented Dec.9,'1913'.

2 SHEETS-SHEET 2.

UNITED sTATEs PATENT o EIoE.

ROYAL E. FRICKEY, OF HEROULT, CALIFOBNIA, ASSIGNOR TO NOBLE ELECTRIC STEEL COMPANY, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF CALIFORNIA.

ELECTRICAL REDUCTION-FURNACE.

Specification of Letters Patent.

Application filed April 29, 1912. Serial No. 693,772.

To all whom it may concern:

Be it known that I, ROYAL E. FRIGKEY, a citizen of the United States, residing at Heroult, in the county of Shasta and State of California, have invented certain new and useful Improvements in Electrical Reduction-Furnaces, of which the following v is a specification.

The hereinafter described invention relates to an improved long and narrow type of electric furnace for the reduction of metals from their ores, and has for its principal object to arrange the electrodes and connect the same to a source of electric energy in such a manner as to dispose of the greater part of the energy in the charge between the electrodes, and thus balance the load on the several phases of the system, and to connect the central electrodes to two phases of the system so that the current passing downward through the central electrodes is greater than that from the end electrodes, whereby thematerial adjacent the center and bottom of the crucible is subjected to the highest temperature resulting in the crucible.-

With the'above mentioned and other objccts in view, the invention consists in the construction and novel arrangement of parts hereinafter fully described, illustrated in the accompanying drawings, and pointed out in the claims hereto appended.

To fully comprehend the invention reference should be had to the accompanying drawings wherein like parts are designated by similar numbers of reference, and in which- Figure 1 is'a side elevation of a metallurgical furnace, one-half in section, disclosing the construction of the furnace and the positioning of the several electrodes therein. Fig. 2, is a transverse sectional View taken on line 22, Fig. 3, disclosing one of the electrodes and the bus bar connecting the same with the transformer. Fig- 3 is top plan view of the furnace and the. transformers, disclosing the electrodes, the transformers and the manner of connecting the same. Fig. 4 is a diagrammatic viewof the electrodes and the manner in which the same are connected to the transformers.

Referring more particularly to the drawings, the numeral 1 designates the'furnace, preferably oblong in shape, constructed with the usual crucible 2, having a suitable refractory lining 3, inclosed by a metallic shell 4, and supported upon a suitable foundation 5. v

The crucible is provided with the usual tap holes 6,through which the molten products are removed and also-with the doors 7 behind which is placed a removable lining so that an opening in the crucible is provided for starting, withdrawing or stopping a run, and suitable apertures 8 are also provided in the crucible, at the front thereof opposite the electrodes for ascertaining the position of the same.

The crucible is provided with the covers 9 constructed of a refractory brick or lining surrounded by a suitable metallic covering 10, and retained in position by suitable clamp arms'll, the covers being provided with a su table opening surrounded by a water jacket 11 and through the center of the jackets extend the electrodes 12', 12 ,12 12 the upper ends of which are guided by the insulated holders 13, which are connected electrically through suitable bus bars 14 with transformers 15.

The depth of the electrodes within the crucible is regulated by a block and tackle 13 and a winding drum 13 Extending upwardly between the alined electrodes are the stacks 16 through which the ore charge is deli :ered into the crucible from any suitable source of supply as by a. charging car, the stacks consisting of brick lined metallic tubes 17, supported by suitable uprights 18 upon which rest suit able transversely extending I-beams 19, the upper edges of which support suitable castings carried by the outer faces of the tubes 17.

Referring more Particularly to Fig. 4, the numerals 15 A-B, 15 BC, 15 C-D, designate the secondaries of three transformers connected to a three phase system on the primary side, either in star or delta fashion, in such a manner that the secondary voltages exist in the delta phase relation to each other, 6. so that with equal secondary voltages and the points 20-A and 20-B, Fig. 4C, joined by a conductor, the usual delta relation would exist.

The circulation of the generated expand- Patented Dec. 9,1913.

ed gases is not essential for the successful The height of the electrodes withinthe cruescape upwardly through the stacks, burning in a suitable housing at thetop'thereof.

In the operation of the furnace, ,the' material a and cible is so adjusted that the energy delivered to the charge under these and to the bath,

is suiiicient to reduce the fiuxesyimpregnate the metal with carbon and silicon; bringthe bath to the temperature necesary to de sulfurize and dephosphorize the metal, and

' to obtain the desired fluidity.

The position of the lower ends of the electrodes which extend into the crucible is determined from time to time by inserting a feeling rod in the apertures8 in the side of the furnace, and the secondary voltage to the electrodes is regulated by the usual fform of regulating means, so that the load is equal on each ofthe three transformers and is of the desired total value.

It will be observed that as the electrodes extend 'downwardly into the crucible for a considerable distance that there is always a conducting path of charge between the same, and the energy dissipated in the charge, comprising the path between twoelect-rodes of one phase depends upon the-voltage of that phase andis independent of the voltage or load on the other phases. In addition to the above mentioned path between the electrodes there is also a pathfrom one elec-' trode to another comprising the charge under two electrodes and the bath at the bottom-of the crucible, the bath having a low resistance in comparison with the charge under the electrodes, the energy passingdownwardly from the ends of the electrodes is concentrated between the ends of the electrodes and the bath.

Itwill also be observed that in connecting the electrodes in the above mentioned manner that the current passing downward under the two middle electrodes is the resultant of the current from two phases and is consequently greater than that from the end electrodes and under the condition of equal voltage on each phase and equal height of the electrodes above the bath, the current under the middle electrodes is approximately 150% of and the energy dissipated approximately 225% of, that under the end electrodes. The current under the middle electrodes being the resultant of that from two phases, the component current in the transformers is not in phase with the corresponding voltage, however, the total energy consists of that dissipated between the electrodes, which is delivered by'the transform ers at unity power factor, and that dissipated under the electrodes, and consequently the power factor diiiers little from unity. As the charge descends'the ore is partly reduced in the stacks and at'the top of the crucible by the ascending generated gases formed by the 're'du'cing'of'ore in the crucible,'but -tl1e principal reduction and carbu- 'retization of the ore takes place in thezone "between the electrodes; the meltingand final.

impregnation with carbon and sillcon, and the desulfiirization and; dephosphorization 'takes place in the vicinity of the ends of the electrodes, especially under the middle electhan under the endelectrodes.

From the above description it will be ap- V v .75 trodes, :as the current thereunder 1s greater .parent that the advantage of the" present structure over the three electrode-type of furnace lies in the fact that a considerable portion of the total energy may be disposed in the charge between the electrodes without disturbing the balance on the several phases, which is an important feature inthe operation of large capacity furnaces.

Having thus fully described the invention what is claimed as new and is desired to be protected by Letters Patent is- 1. In an electrical reduction furnace of the long and narrow type, the combination with a crucible, of feed stacks through which ores are fed to said crucible, end electrodes, and a plurality of middle electrodes extending downwardly through a conducting charge into said crucible, said electrodes arranged in spaced relation and in alinement with each other, a source of electnc energy,

said electrodes being so connected to the said source of electric energy'that the energy delivered by the middle electrodes is greater, than that delivered by the end elec-' trodes substantially as shown and for the purpose described. 2. In an electrical reduction furnace of the long and narrow type, the combination .with a crucible, of feed stacks through which charges of ore are fed to said crucible, a pair of central electrodes and a pair of end electrodes extending downwardly through a' conducting charge into said "crucible, said electrodes arranged in spaced relation and in alinement with each other, a plurality of transformers associated with said electrodes the primary circuits of which are connected to a three phase system wherebya concentrated zone of energy is produced under the central electrodes.

3. In an electrical reduction furnace of the long and narrow type, the combination with a, crucible, of feed stacks through which charges of ore are fed to said crucible, a plurality of electrodes arranged in a row and extending into said crucible, said electrodes connected to a three phase system in such a manner that the phase-angle is 60 degrees between voltages supplied to adjacent pairs of electrodes.

4:. In an electrical reduction furnace of the long and narrow type, the combination with a I crucible, of feed stacks through which charges of ore are fed to said crucible, a pair of central electrodes and a pair of end electrodes extending downwardly through a conducting charge into said crucible, said electrodes arranged in spaced relation and in alinement with each other, a plurality of transformers associated with said electrodes, the primary circuits of which are connected '10- to a three phase system in star fashion ROYAL E. FRICKEY.

Witnesses:

JOHN CRAWFORD, Jr., WVM. MCNABB. 

